Effect of Anisotropic Shape on Ship Wakes in Presence of Shear Current of Uniform Vorticity

2016 ◽  
Author(s):  
Yan Li ◽  
Simen Å. Ellingsen
Keyword(s):  
Aspect Ratio ◽  
Three Dimensional ◽  
Ship Waves ◽  
Aspect Ratios ◽  
Asymptotic Expressions ◽  
Shear Current ◽  
Ship Wakes ◽  
Surface Disturbance ◽  
Dimensional Shape ◽  
Three Dimensional Shape

We analyze the interactions between a subsurface shear current of uniform vorticity and a moving surface disturbance of anisotropic shape which generates surface gravity waves. The problem extends previous analysis of ship waves in the presence of a shear current varying linearly with depth, now also accounting for the three dimensional shape of real ships, in order to study the interplay of aspect ratio and the shear current. Based on general solutions derived previously, we apply an elliptical Gaussian pressure disturbance at the surface moving at constant velocity as a model for a real “ship”. Wave contributions in the far field and expressions for the Mach angle (of maximum wave amplitude) based on asymptotic expressions for high Froude numbers, are derived thereafter. Through numerical calculations we present wave patterns, as well as Kelvin and Mach angles, at moderate Froude numbers under different shear strenghts and aspect ratios. Results show that the aspect ratio has negligible effect on the value of the critical shear vorticity and Kelvin angle, whereas a subtle interplay of aspect ratio and shear strenght is found to affect the Mach angle at moderate Froude numbers.

Four Dimensions of Diamond T: Combination Trade Marks of Colours And Shapes

2006 ◽  
Vol 37 (4) ◽  
pp. 583
Author(s):  
Michael McGowan
Keyword(s):  
Three Dimensional ◽  
Trade Mark ◽  
Fourth Dimension ◽  
Trade Marks ◽  
Four Dimensions ◽  
Trade Mark Law ◽  
Dimensional Shape ◽  
Three Dimensional Shape

This article examines the relatively new fields of colour and shape trade marks. It was initially feared by some academics that the new marks would encroach on the realms of patent and copyright.  However, the traditional requirements of trade mark law, such as functionality and descriptiveness, have meant that trade marks in colour and shape are extremely hard to acquire if they do not have factual distinctiveness. As colour and shape trade marks have no special restrictions, it is proposed that the combination trade mark theory and analysis from the Diamond T case should be used as a way to make them more accessible. The combination analysis can be easily applied because every product has a three dimensional shape and a fourth dimension of colour.

Acoustic Analysis of Detailed Three-Dimensional Shape of the Human Nasal Cavity and Paranasal Sinuses

2017 ◽  
Author(s):  
Tatsuya Kitamura ◽  
Hironori Takemoto ◽  
Hisanori Makinae ◽  
Tetsutaro Yamaguchi ◽  
Kotaro Maki
Keyword(s):  
Nasal Cavity ◽  
Paranasal Sinuses ◽  
Acoustic Analysis ◽  
Three Dimensional ◽  
Dimensional Shape ◽  
Three Dimensional Shape

scholarly journals The Effect of Material Properties on the Perceived Shape of Three-Dimensional Objects

i-Perception ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 204166952098231
Author(s):  
Masakazu Ohara ◽  
Juno Kim ◽  
Kowa Koida
Keyword(s):  
Material Properties ◽  
Regional Variation ◽  
Three Dimensional ◽  
Mean Square ◽  
Viewing Condition ◽  
Three Dimensional Objects ◽  
Transparent Objects ◽  
Dimensional Shape ◽  
Local Root ◽  
Three Dimensional Shape

Perceiving the shape of three-dimensional objects is essential for interacting with them in daily life. If objects are constructed from different materials, can the human visual system accurately estimate their three-dimensional shape? We varied the thickness, motion, opacity, and specularity of globally convex objects rendered in a photorealistic environment. These objects were presented under either dynamic or static viewing condition. Observers rated the overall convexity of these objects along the depth axis. Our results show that observers perceived solid transparent objects as flatter than the same objects rendered with opaque reflectance properties. Regional variation in local root-mean-square image contrast was shown to provide information that is predictive of perceived surface convexity.

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